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~G:, .. Zephyrhills Professional Center Site Pasco County, Florida GDE Job No. 05-432 Page 5 the Unified Soils Classification System) and less than 5 percent organics by weight. However, material containing up to 35 percent fines (materials conforming to SC or SM in the Unified Soil Classification System) may be utilized as structural fill, if their plasticity index is less than 30, and the working subgrade is at least 2 feet above water or groundwater level. If fill material with higher fines content is used (< 35 percent fines), the materials will require the use of compaction equipment designed for clayey soils. This includes a sheeps foot or vibratory pad foot roller. In addition, a disk could be required to assist with drying the clayey soils in order to place them at or near their optimum moisture content. These materials must be placed at a 6-inch thick maximum lift so that they can be effectively compacted with a vibratory pad foot roller. Soil Suitabilitv Based on our test boring results (Figure 3), in general, the soil materials encountered in the borings to approximate depths of 4 to 8 feet should be satisfactory as a source of structural fill (if necessary). Stratum 1 soils can be utilized as fill, excluding any organic (root) or debris (trash) material. Note: Pasco County requires that ponds bottoms be excavated no closer than within 1 O-feet of the limestone layer. Placement Fill should be placed in lifts not to exceed one foot thick. The fill material should be compacted to at least 95 percent of its modified Proctor maximum dry density (ASTM 0-1557). Confined areas, such as utility trenches, should be compacted with manually operated vibratory compaction equipment. Pavement Recommendations We have not been provided with traffic distribution or frequency, nor have we performed Limerock Bearing Ratio (LBR) testing on the subgrade soils. We have assumed that a 20-year pavement life is desired, and that the coefficient of terminal serviceability is 2.5. Further assumptions are that the in- place soils, when compacted to at least 95 percent of their modified Proctor maximum dry density will exhibit a minimum LBR value of 15, and that the total number of equivalent 18-kip axle loads will be less than 100,000. Based on these assumptions, we recommend the following asphaltic concrete pavement section: Section Descri tion Thickness in Surface Course Type S-1 or S-3 Asphaltic Concrete with minimum Marshall stability of 1500 Ibs. 1.5 Com acted to at least 95 ercent of the maximum laborato Marshall densi . Base Course Limerock having a minimum LBR of 100 and compacted to at least 98 percent of its modified Proctor maximum dry density (ASTM D-1557). If the bottom of the base will be within 18 6 inches of the seasonal high groundwater level, then a moisture tolerant base will be re uired such as shell crushed concrete or soil cement. Subbase Stabilized' to a minimum LBR of 40 and compacted to at least 95 percent of the modified 6 Proctor maximum d densi ASTM D-1557 , "Requires blending either shell or Iimerock with in-place surficial sand. Typical composite samples of subbase are comprised of 50% in-place !land and 50% imported material (limerock or shell). The previously recommended pavement section was developed using design guidelines publiShed by the Florida Department of Transportation, Division of Road Operations. We recommend that methods and materials used for pavement construction conform to applicable sections of the Florida Department of Transportation Standard Specifications for Road and Bridge Construction, 1999 Edition. We further recommend that LBR tests be performed on the on-site soils prior to bidding the project to confirm that an LBR of 15 is available and to determine the appropriate volume of shell or Iimerock that